Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology, who boasted about her unrivalled beauty. It was one of the 48 constellations listed by the 2nd century Greek astronomer Ptolemy (there are currently 88 known constellations today). It is easily recognizable due to its distinctive 'W' shape, formed by five bright stars. It is bordered by Andromeda to the south, Perseus to the southeast, and Cepheus to the north. Within the 'W' lies Cassiopeia A - the remnant of a supernova that took place approximately 300 years ago (11,000 light-years from Earth).